NITRIFYING POWER OF SOILS AT DIFFERENT DEPTHS. U7 
Figures 11 and 12 present the results obtained from samples of soil 
from plats 240, 250, 260, and 270. The fields in which these plats are 
_ DEPTH AT WHICH SAMPL ES WERE TAAEN. 
Or06" 67012" 127018" 187024" 
a) 
IN 
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N 
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. 
S 
AS 
S 
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. 
S 
S 
cS 
| 
g 
S| 
PARTS PER MILLION OF WITROGEN AS NITRATES. 
Fic. 9.—Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
from plat 220, Truckee-Carson Experiment Farm. Original nitrate present in samples: Depth, 0 to 6 
inches, 7.68 parts per million; 6 to 12 inches, 6.91; 12 to 18 inches, 10; 18 to 24 inches, 5.64; 24 to 36 inches, 6. 
located have been merely leveled and left fallow, receiving regular 
applications of irrigation water. The field containing plats 240 and 
250 is never cultivated, while that containing plats 260 and 270 is 
DEPTH AT WHICH SAMPLES WERE TAKEN. 
0706" 6 r0l2" 27018" 187024" 2470 36" 
pf 
\ 
J, Ne Ss a 
Pa i XS \ 
VEE “SNS 7 
7 » 
ee ws eo 
nitrates Plat 220 $< | 
PARTS PER MILLION OF NITFOGEN AS NITRATES. | 
PARTS PER MILLION OF CHLORIOS AND SULPHATES. 
Fic. 10.—Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
from plat 230, Truckee-Carson Experiment Farm. Original nitrate present in samples: Depth, 0 to 6 
inches, 10 parts per million; 6 to 12 inches, 8.16; 12 to 18 inches, 5; 18 to 24 inches, 4.56; 24 to 36 inches, 9.6. 
cultivated according to thorough summer-fallow methods. As the 
conditions are abnormal it is not surprising that the curves of chlorids 
78011°—Bul. 211—11——_3 
